1. Field of the Invention
The present invention generally relates to a method and system for determining a communication mode. More particularly, the present invention relates to a method and system for determining a communication mode between Mobile Stations (MSs).
2. Description of the Related Art
In a communication system, there are, by and large, two communication modes for communicating between a transmitting MS (i.e. a source MS (MS_S)) and a receiving MS (i.e. a destination MS (MS_D)). Those modes are the cellular communication mode and the Peer-to-Peer (P2P) communication mode. In the cellular communication mode, MS_S communicates with MS_D via a Base Station (BS), whereas in the P2P communication mode, MS_S communicates directly with MS_D without the aid of the BS.
With reference to FIG. 1, the conventional cellular communication mode and P2P communication mode will be described below.
FIG. 1 illustrates a cellular communication-mode operation and a P2P communication-mode operation in a conventional communication system.
Referring to FIG. 1, the communication system includes a BS 101, a source MS 103 (MS_S), a first destination MS 105 (MS_D 1), and a second destination MS 107 (MS_D 2).
In the illustrated example of FIG. 1, MS_S communicates with MS_D 2 in the cellular communication mode. The reason MS_S uses the cellular mode is because MS_D 2 is located outside a maximum distance of the signal transmitted by MS_S. The maximum distance, which is known to both MS_S and MS_D 2, is a distance within which it is preferable that MS_S communicates with MS_D 2 using the P2P communication mode. For instance, the maximum distance preset by the communication system may be denoted as d. In the example of FIG. 1, the distance between MS_S and MS_D 2 is greater than d by a distance Δ. Since the total distance between MS_S and MS_D 2 is d+Δ, MS_D 2 is not located within d and MS_S and MS_D 2 use the cellular communication mode. Conversely, since MS_D 1 is located within the distance d, MS_S communicates with MS_D 1 in the P2P communication mode.
However, even though MS_D 1 is within the distance d, if no resources are available for P2P communications between MS_S and MS_D 1, or if an agreement has not been reached between MS_S and MS_D 1 with respect to the P2P communications, MS_S communicates with MS_D 1 using the cellular communication mode.
To facilitate P2P communications between MS_S and MS_D, as described above, a mutual agreement on the P2P communication should be made and preparation for the P2P communications should be completed. The P2P communication preparation amounts to setting MS_S to P2P signal transmission and setting MS_D to P2P signal reception.
Accordingly, when an MS is to communicate with another MS, they must undergo a series of processes each time, including a communication mode selection and a mutual agreement on the communication mode. These processes are time consuming and inconvenient for the MS users. Moreover, even in a situation where the P2P communication mode is preferable, they cannot operate in the P2P communication mode without reaching an agreement on the P2P communication mode.